To speedily perform a fuel filling operation carried out in racing of motorcycles, in Japanese Patent Document JP-UM-A-3-27869, there has been known the fuel filling port structure of a fuel tank which operates a lid such that the lid is pushed downwardly to open a fuel filling port in response to a pushing manipulation of a fuel supply device to the fuel filing port and the lid closes the fuel filling port by simply removing the fuel supply device from the fuel filling port.
Here, the fuel filling port structure of a fuel tank disclosed in the above-mentioned Japanese Patent Document is configured such that the lid is biased by a spring toward a side that the fuel filling port is closed and hence, even when a pushing force acts on the lid due to an object other than the fuel supply device, the lid opens the fuel filling port.
The present invention has been made in view of the above-mentioned circumstances and it is an object of the present invention to provide a fuel filling port structure of a fuel tank which can prevent the opening of a fuel filling port due to an object other than a fuel supply device.